Listeriosis outbreak expands to 40 cases and seven deaths

Oct 4, 2002 (CIDRAP News)  A listeriosis outbreak in Pennsylvania and neighboring states has expanded to 40 cases, with seven deaths and three miscarriages or stillbirths, the Centers for Disease Control and Prevention (CDC) announced yesterday. The source of the outbreak remained unknown.

The outbreak has included 14 cases in Pennsylvania, 11 in New York City, 3 elsewhere in New York state, 4 in New Jersey, 4 in Delaware, 2 in Maryland, 1 in Connecticut, and 1 in Michigan, the CDC said. There were two miscarriages or stillbirths in New Jersey and one in Delaware. All the patients were hospitalized.

The outbreak involved 26 cases and four deaths when the CDC first reported it Sep 18. Cases began occurring in the summer and continued through September.

Listeria monocytogenes isolates from 40 patients have been found to have matching DNA patterns, strongly suggesting that patients acquired the infection from the same food, the CDC said. Federal and state officials were continuing to look for the source of the outbreak.

The CDC and state health departments have analyzed L monocytogenes isolates from another 30 patients in the same region and found they are a different strain, the agency said. Testing of isolates from more than 15 other patients is still under way.

About 2,500 listeriosis cases occur annually in the United States, the CDC said. The agency advised people with weakened immune systems, the elderly, and pregnant women to avoid foods that could be contaminated with Listeria. Those include processed meats, such as hot dogs and deli meats (unless thoroughly reheated), and soft cheeses such as feta, Brie, Camembert, and blue-veined and Mexican-style cheeses.